<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>金字塔</title>
		<script type="text/javascript">
			function jizita(){
			document.write("<h1 style='text-align: center;'>打印倒正金字塔直线</h1>");
			for(var i=400;i>0;i-=50){
			var ss= i+'px';
			document.write("<div style='margin: auto;width :"+ss+";border-bottom:1px dashed black ;'><br /></div>");
			}
			document.write("<div style='margin: auto;width :10px;border-bottom:1px dashed black ;'><br /></div>");
			for(var i=50;i<=400;i+=50){
			var ss= i+'px';
			document.write("<div style='margin: auto;width :"+ss+";border-bottom:1px dashed black ;'><br /></div>");
			}
			}
		</script>
	</head>
	<body onload="jizita()">
		
	</body>
</html>
